Field of the Invention
The present invention relates to novel spiroothocarbonate compounds and also to copolymers containing them as one of the components. The compounds and copolymers of the present invention are novel and usable for molding materials, composite materials, injection materials, sealing materials, medical and dental materials, paints, adhesives and like materials.
It is well known that polymerizable monomers such as acrylonitrile, vinyl acetate, methyl methacrylate, styrene, ethylene oxide and epichlorohydrin shrink to a large extent upon polymerization. Shrinkage in volume of thermosetting resins such as epoxy and phenol resins upon curing causes a large trouble in the fields of injection molding, sealant application, adhesive application and the like.
A material undergoing no shrinkage upon polymerization would realize precise molding due to improvement in dimensional accuracy and minimization of clearance generation and increase the strength or adhesiveness of finished articles thanks to reduction of internal stress.
Spiroorthocarbonates are known monomers that exhibit expansion in volume upon polymerization. Ring-opening polymerization of spiroothocarbonates are generally conducted by cationic polymerization with a Lewis acid such as borontrifluoride ether complex. Some end-uses, however, favor a system where the ring-opening polymerization is effected by radical polymerization with accompanying volume expansion occurs.
Spiroorthocarbonates having exomethylene group are useful monomers, which polymerize, reportedly, not only by cationic polymerization but also by radical polymerization to yield polymers.
It has also been reported that spiroothocarbonates having an exomethylene group at the .alpha.-position of its ether oxygen and consisting of two 5-membered rings ("1" shown below) undergo only vinyl polymerization upon radical polymerization, to yield crosslinked polymers [H. Tagoshi and Endo, J. Polym. Sci., Chem. Ed., 27, 1415 (1989)]. ##STR3##
Further it has been reported that spiroorthocarbonates having exomethylene group at the .beta.-position of its ether oxygen and consisting of two 6-membered rings ("2" shown below) undergo ring-opening isomerization upon solution radical polymerization, to yield polyether carbonates [T. Endo and W. J. Bailey, J. Polym. Sci., Polym. Lett. Ed., 13, 193 (1975)] ##STR4##
The compound shown by 2, however, has the problem of yielding a crosslinked polymer upon bulk radical polymerization, thereby exhibiting a small expansion on polymerization.